The petroleum refining industry has long been faced with the need to increase the efficiency of the production of commodity petroleum products from petroleum feedstock. In addition, the demand for particular commodity petroleum products has also increased. Furthermore, the quality of the commodity petroleum products produced has also been subject to increasing demands of stability and purity. For example, while many prior art processes have been described that produce commodity petroleum products with shorter hydrocarbon chain lengths from petroleum feedstocks containing higher hydrocarbon chain length precursors, the resulting commodity petroleum products are often unstable due to chemical species produced during the conversion process (such as but not limited to high olefinic content) or possess undesirable characteristics from a performance perspective (such as, but not limited to, low octane ratings) or an environmental perspective (such as, but not limited to, high sulfur content).
In addition, the petroleum industry is faced with the prospect of using multiple sources of petroleum feedstock that vary significantly in chemical content. In order to cope with the changing composition of the petroleum feedstock, methods must be developed that are flexible enough to be used with a variety of petroleum feedstocks without substantial alterations of the method. Such flexibility would expand the natural resources (i.e., petroleum feedstocks) available for the production of commodity petroleum products and further enhance the efficiency of production of commodity petroleum products.
In addition to being flexible enough to accommodate a variety of petroleum feedstocks as a starting material, production efficiency could be enhanced by a method flexible enough to produce a commodity petroleum product with a desired set of properties, such as but not limited to, a desired hydrocarbon chain length, from a given petroleum feedstock. For example, economic conditions or supply and demand in the marketplace may dictate that a lubricant with a higher hydrocarbon chain length than gasoline is a preferred commodity petroleum product for a period of time. Therefore, a method flexible enough to produce a variety of commodity petroleum products from a petroleum feedstock would be an advantage in meeting the demands of a changing marketplace and would further maximize the value of the commodity petroleum products.
Crude oil can be effectively used as an example. Crude oil is a complex mixture that is between 50% and 95% hydrocarbon by weight (depending on the source of the crude oil). Generally, the first step in refining crude oil involves separating the crude oil into different hydrocarbon fractions, such as by distillation. A typical set of hydrocarbon fractions is given in Table 1. An analysis of Table 1 shows that gasoline has a hydrocarbon chain length of 5-12 carbon atoms and natural gas has a hydrocarbon chain length of 1-4 carbons while lubricants have a hydrocarbon chain length of 20 carbons and above and fuel oils have a hydrocarbon chain length of 14 and above. In order to maximize the value of a single barrel of crude oil, it would be advantageous to develop a process to convert the petroleum feedstock with longer hydrocarbon chain lengths into a desired commodity petroleum product with shorter hydrocarbon chain lengths, thereby maximizing the potential use and value for each barrel of crude oil. While commodity products with hydrocarbon chain lengths of 15 or less are generally desirable and more valuable, conditions in the marketplace may make the production of other commodity products more desirable.
In addition, certain types of petroleum feedstocks are not suitable for use as starting materials in petroleum refining operations. For example, bitumen is a complex mixture of hydrocarbon molecules that generally has a viscosity too great for use in standard petroleum refining techniques. Bitumen includes what are commonly referred to as tar and asphaltic components. However, if bitumen and other similar petroleum feedstocks could be treated to reduce the higher molecular mass components, they would become useful in petroleum refining operations and could yield a number of commodity petroleum products. Such a process is referred to as “petroleum upgrading”. Therefore, it would be advantageous to develop a process to convert such complex hydrocarbon feedstocks to petroleum feedstocks and/or commodity petroleum products capable of further refining.
One important consideration for any method of processing petroleum feedstock to produce commodity petroleum products is the economic aspect. Current technologies exist that allow the processing of petroleum feedstocks with high hydrocarbon chain lengths into commodity petroleum products with shorter hydrocarbon chain lengths. However, many of these methods require substantial amounts of energy to be input into the system making them a less desirable alternative. In addition, many of the prior art processes are multi-stage processes requiring multiple steps and or multiple plants or facilities for the initial and subsequent processing. For example, a given process may require three steps to produce gasoline from a given petroleum feedstock and then require additional processes to remove contaminants from the produced gasoline or to enhance the performance characteristics of the gasoline. A one-step method of producing desired commodity petroleum products from a given petroleum feedstock would be of substantial value to the petroleum industry.
In order to achieve the above stated objectives, the prior art has utilized a variety of hydrocarbon cracking reactions to reduce the hydrocarbon chain length of various petroleum feedstocks. The main problem to be solved for effective processing of any type of petroleum feedstock via a cracking reaction is a problem of the control of the cracking reaction in conditions that provide combination of high processing rate and high conversion efficiency with a maximum simplicity, reduced capital expenditures for plant construction, maintenance and operation and economic efficiency at minimum energy expense.
As discussed above, only methods that allow the efficient propagation of hydrocarbon chain cracking reactions can provide the high processing rates necessary for industrial and commercial use. Furthermore, in one particular embodiment, such methods should utilize low pressures and temperatures during all phases of the cracking reaction in order to minimize operational costs and increase safety. Realization of such methods requires that the problems of cracking initiation and stimulation of chain cracking propagation at lowered temperatures be solved.
The present disclosure provides such a solution by providing a simple and efficient method for the self-sustaining radiation cracking of hydrocarbons. The method disclosed provides for the deep destructive processing of hydrocarbon chains utilizing hydrocarbon chain decomposition under a wide variety of irradiation conditions and temperature ranges (from room temperature to 450° C.). Several embodiments of such method are disclosed herein, including; (i) a special case of radiation-thermal cracking referred to as high-temperature radiation cracking (HTRC); (ii) low temperature radiation cracking (LTRC); and (iii) cold radiation cracking (CRC). The technological results of this disclosure include, but are not limited to: (i) the expansion of the sources of petroleum feedstocks for the production of commodity petroleum products; (ii) increasing the degree of petroleum feedstock conversion into usable commodity petroleum products; (iii) maximizing the yields of a variety of commodity petroleum products from petroleum feedstocks; (iv) upgrading the quality of various petroleum feedstocks; (v) and increasing the quality commodity petroleum products by minimizing undesirable contaminants (such as but not limited to sulfur) that may be present in the commodity petroleum products as a result of unwanted chemical reactions; (vi) increasing the stability of the commodity petroleum products produced by minimizing or preventing undesirable chemical reactions; (vii) providing a method flexible enough to produce a variety of commodity petroleum products from a given petroleum feedstock. The methods of the present disclosure provide these, and other benefits while reducing the energy required, simplifying the physical plant required to implement the methods and reducing the number of steps involved in the process as compared to prior art methods.